The shafts used in fine handmade fly fishing rods are normally composite structures made from multiple elongated strips of wood such as bamboo. Such shafts are ordinarily made with a regular polygonal cross section, such as pentagonal or hexagonal and almost universely are made with a progressive taper from a relatively broad cross section at the handgrip end to a slender cross section at the tip. Thus, each of the individual wooden strips used in the shaft must be formed with an accurately tapering triangular cross section. The cross sectional dimensions of each strip in the rod at any given point along its length must be identical to the corresponding dimensions of the other strips to within a few thousandths of an inch for proper performance of the finished rod. Moreover, the desired taper of the shaft cross section and hence the desired taper of each individual strip is ordinarily not uniform along the length of the rod. The desired configuration of each strip may therefore include a relatively rapidly tapering portion merging gradually into a portion having a somewhat lesser taper or decrease in cross sectional dimensions per unit length which section in turn merges gradually into another section having an even lesser taper.
Such strips have generally been made by planing each strip after preliminary treatment of the wood to the desired configuration utilizing a planing form. One type of planing form which has been utilized heretofore is described at pages 67 through 71 of the treatise A Master's Guide to Building a Bamboo Fly Rod by Evrett Garrison and Hoagy B. Carmichael (Martha's Glenn Publishing Co., Katonah, N.Y., 1977). This type of planing form includes a pair of elongated rectangualar bars or members each having a longitudinally extensive beveled surface along one edge. The bars are juxtaposed with one another so that their respective beveled surfaces cooperatively define a generally V-shaped groove. Ordinarily, the beveled surfaces are themselves tapered so that the depth and width of the groove is defined when the bars are disposed parallel to one another at a predetermined, uniform taper per unit length. Control or differential screws are provided at spaced intervals along the length of the bars to permit adjustment of the bars or members towards and away from one another so as to vary the width and depth of the groove. Each such control screw has two screw threads of slightly differing pitch, each such thread extending over a portion of the length of the screw. The portion of greater pitch is threadedly engaged with one of the bars and the portion of lesser pitch is engaged with the other so that rotation of the control screw in one direction will draw the adjacent portions of the members closer to one another and thereby narrow the groove in the vicinity of the control screw, but rotation of the screw in the opposite direction will have the opposite effect.
By adjusting the settings of the control screws, the width and degree of taper of the groove adjacent each control screw can be adjusted until the groove has the desired configuration for the particular rod to be constructed. However, with the planing form described above, such adjustment has been an extremely painstaking and time-consuming process. To achieve a nonuniform taper per unit length, the settings of the control screws must be such that the members are distorted from their normal straight condition. Thus, each control screw will ordinarily be under a substantial load when first adjusted to the desired setting. However, when the next adjacent control screw is adjusted to its desired setting, such load may be removed or reversed in direction, thus producing relative motion or slop between the first adjusted control screw and the members and altering the width of the groove at the first adjusted control screw. Therefore, with the form described above, it has generally been necessary to readjust all of the control screws several times to achieve the desired pattern of groove widths along the length of the form. Whenever the setting of the form is to be changed to produce a rod of a different design, the entire process must be repeated again. Accordingly, the time and effort consumed in setting the control screws has been a substantial problem heretofore.